1. Field of the Invention
This invention relates to dyeing aids and to a process for the single-bath, single-stage dyeing of textile fibers.
2. Discussion of Related Art
Cotton contains natural impurities, for example waxes, wax-like substances, proteins, seed shells, fruit husks and pectins and also impurities which are applied as foreign substances in the course of processing, for example paraffins and/or mineral oils. The impurities in wool, regenerated fibers, such as viscose rayon, and synthetic fibers, such as polyester and polyamide, emanate from the treatment of these materials with finishes (Chwala/Anger: "Handbuch der Textilhilfsmittel", pages 526-528, 537, 558 et seq., Verlag Chemie Weinheim, 1977). To obtain uniformly dyed textile fibers, particularly cellulose-containing textile fibers, the textile material is normally subjected to a pretreatment. The object of the pretreatment is to remove the impurities mentioned by way of example above as completely as possible from the fibers in order thus to provide the fibers with the relatively high degree of hydrophilicity and absorbency required for the subsequent finishing processes. In dyeing processes above all, inadequate hydrophilic properties and inadequate absorbency of the textile material result as early as the dye absorption phase in uneven dyeing which is very difficult or impossible to correct.
However, the pretreatment is attended by the disadvantage that it has to be carried out in several stages. Accordingly, to shorten the processes involved in the dyeing of textiles, processes have recently been developed which eliminate the need for the separate pretreatment step (Chwala/Anger: "Handbuch der Textilhilfsmittel", pages 528-529, Verlag Chemie Weinheim, 1977). Single-bath, single-stage dyeing is one such process. In this process the textile material is pretreated and dyed in a single stage. The baths contain the chemicals required for the pretreatment, such as wetting agents, detergents, dispersants, leveling agents and/or alkalis, and also dyes. The single-bath/single-stage dyeing process described in DE 36 43 752 for mixtures of polyester fibers and cellulose fibers dyeable in the absence of carriers is carried out in the presence of dispersion and reactive dyes and, optionally, auxiliaries at pH values of 6 to 8.5 and at temperatures of from 90.degree. to 105.degree. C.
However, the stringent requirements in regard to level dyeing, depth of color and fastness of the textile material often cannot be satisfactorily met by the known single-bath, single-stage dyeing processes. Accordingly, the problem addressed by the present invention was to develop dyeing aids which, used in single-bath single-stage dyeing processes, would produce uniform and brilliant colors on the textile material. In addition, the performance characteristics of the dyed fibers, such as fastness to light, fastness to rubbing and wet fastness values, would not be adversely affected by the use of such aids.